Carbon nanotubes offer a unique combination of physical properties and chemical stability (1). Carbon nanotube networks are anticipated to be used in applications such as reinforcements for lightweight and high performance composites, multifunctional membranes, electronics, and electrodes for energy storage devices (2-6). However, most assembled carbon nanotube networks are based on weak van der Waals interactions between the nanotubes (7). As a result, the reported experimental mechanical strength, and electrical and thermal conductivities are several orders of magnitude lower than theoretical predictions due to a lower mechanical pulling resistance between nanotubes, and a higher electron and phonon scattering at the junctions between nanotubes. Recently, there has been success in transforming these van der Waals interactions into covalently bonded molecular junctions (8-29). For example, electron (11,19-21) and ion (11) irradiation as well as electrical current sources (23-27) have been used to modify the structure and morphology of nanocarbon materials. However, these rearrangement studies achieved only local changes at junctions in a few individual nanotubes (11-21,25) and the destruction of carbon layers on electrical breakdown (23,26,27). Furthermore, the reported reconstruction methods require high to extremely high temperature (750-2,200° C.) conditions (20,22,28), making them power-intensive and incompatible with various scalable processes. Therefore, developing a fast and scalable method for reproducibly creating particular types of covalently bonded C—C junctions and sp2 molecular structures in nanocarbon networks that result in repeatable physical properties has remained a fundamental challenge.